Rotary pivot unit

ABSTRACT

A positioning apparatus includes a housing having a chamber. The vane is rotatably movable within the chamber. An arm is coupled to the vane.

BACKGROUND AND SUMMARY OF THE INVENTION

[0001] The present invention relates generally to powered positioning devices and, more particularly, to a powered pivot unit for moving or positioning industrial tooling.

[0002] Pivot units are commonly used in industrial applications for positioning tooling or work pieces during forming and machining operations. The previously known devices include a pneumatically or hydraulically actuated linear piston cylinder which causes one or more arms to move through a desired range of rotational motion to position the tool or work piece. These devices are often large clamps equipped with a toggle mechanism to achieve the rotational motion of the tool mount. Unfortunately, the toggle mechanism exhibits a torque per rotation angle curve which is not linear. Because the tooling or components to be rotated may weight 100 pounds or more and are often mounted 48 inches from the pivot point, existing pivot units may be unable to lift the tool.

[0003] Many conventional pivot units use a linear fluid cylinder coupled to the linkage to provide the lifting force. The conventional pivot units have cylinders separately attached to a body. The stroke of the fluid cylinder is directly proportional to the amount of rotation available at the tool mounting end. In an attempt to conserve the amount of actuating fluid required, existing manufacturers provide families of power pivot units equipped with a variety of differently sized cylinders. Long cylinders are used if large rotation angles are desired. Large diameter cylinders are used to lift heavy loads. Therefore, an undesirably large number of assemblies must be maintained in inventory to provide manufacturing flexibility. The use of elongated fluid cylinders also creates a relatively large and unwieldly pivot unit assembly which requires extra space in the end use manufacturing plant. Also, service of the linkage or toggle mechanism requires that the tool holding portion be disassembled.

[0004] In accordance with the teachings of the present invention, a preferred embodiment of a rotary pivot unit includes a rotary actuator which provides a generally constant torque output over the entire operating range of pivot angles. In another aspect of the present invention, the rotary actuator includes a rotary vane which is positioned on an opposite side of the pivot point relative to the rotating arm assembly. This effectively counter-balances the tooling to reduce the torque required to lift or position the tool. A further aspect of the present invention provides 105 degrees of available rotation from a single rotary actuator. Because the rotary pivot unit of the present invention utilizes a rotary vane within an arcuate chamber, less pressurized fluid is required to obtain the full 105 degrees of rotation when compared to linear fluid cylinders.

[0005] Yet another aspect of the present invention includes stops, shocks and switch assemblies which are adjustable in generally 15 degree increments throughout the full 105 degree range of rotation.

[0006] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the present invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0008]FIG. 1 is a perspective view of a rotary pivot unit constructed in accordance with the teachings of the present invention;

[0009]FIG. 2 is an exploded perspective view of the rotary pivot unit of the present invention;

[0010]FIG. 3 is a side elevational view of the rotary pivot unit of the present invention depicting an arm assembly in a first or upright position;

[0011]FIG. 4 is a side elevational view of the rotary pivot unit of the present invention depicting the arm assembly in a rotated second position;

[0012]FIG. 5 is a top elevational view of the rotary pivot unit of the present invention;

[0013]FIG. 6 is a front elevational view of the rotary pivot unit of the present invention;

[0014]FIG. 7 is a rear elevational view of the rotary pivot unit of the present invention;

[0015]FIG. 8 is a bottom elevational view of the rotary pivot unit of the present invention;

[0016]FIG. 9 is a cross-sectional view of the rotary pivot unit of the present invention taken along line 9-9 shown in FIG. 5; and

[0017]FIG. 10 is a graph depicting lifting capacity per distance from the axis of rotation of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018]FIGS. 1 and 2 show the preferred embodiment of a rotary pivot unit 20 constructed in accordance with the teachings of the present invention. Pivot unit 20 includes an actuator assembly 22, an arm assembly or positioning bracket 24 and a rotary status controller 26. Arm assembly 24 is drivingly interconnected to actuator assembly 22 via drive pins 28. In FIG. 1, arm assembly 24 is shown in a fully upright first position abutting a first dowel pin 30. Based on the position of a second dowel pin 32, arm assembly 24 may rotate about an axis 34 to a second position shown in FIG. 4. The full stroke of actuator assembly 22 is substantially equivalent to 105 degrees of rotation. Actuator assembly 22 includes a plurality of apertures 36 for receipt of second dowel pin 32. In this manner, a range of arm rotation less than 105 degrees may be defined. Apertures 36 are positioned in 15 degree increments from each other.

[0019] An additional functional advantage of using rotary pivot unit 20 includes versatile mounting. Specifically, actuator assembly 22 includes a first mounting surface 38 and a second mounting surface 40 for coupling rotary pivot unit 20 to a factory floor, a stantion, a workbench or the like. An exemplary bench 42 is shown as a suitable mounting structure in FIG. 1. Actuator assembly 22 also includes a plurality of apertures 43 for receipt of fasteners (not shown) for coupling rotary pivot unit 20 to bench 42. Arm assembly 24 includes a tool mounting surface 44 for mounting an exemplary tool 45. Tool mounting surface 44 is positioned substantially orthogonally to second mounting surface 40 when arm assembly 24 is in the fully upright position.

[0020] With reference to FIGS. 2-4, actuator assembly 22 includes a body 46, a first cover plate 48, a second cover plate 50 and a vane 52. Body 46 is a generally plate-like structure having an arcuately-shaped bore 54 extending therethrough. A chamber 55 is formed once first cover plate 48 and second cover plate 50 are coupled to body 46 thereby enclosing bore 54. Body 46 includes a pair of inlet ports 56 and two pair of outlet ports 58 communicating with chamber 55. Each pair of ports includes one aperture preferably threaded for receipt of {fraction (1/4)} N.P.T. fittings. The other port of each pair is threaded to accept G {fraction (1/4)} fittings. Inlet ports 56 and outlet ports 58 each include an orifice 60 consisting of a relatively small diameter passageway communicating with chamber 55. Orifice 60 serves to reduce the volume flow rate of pressurized fluid entering the chamber and minimize possibly high internal impact loads. For convenience to the user, first cover plate 48 and second cover plate 50 each include two pair of inlet ports 56 as well.

[0021] Pin apertures 62 and 64 extend through body 46, first cover plate 48 and second cover plate 50. A third dowel pin 66 is positioned within pin aperture 62. A fourth dowel pin 68 is positioned within aperture 64. Only first cover plate 48 and second cover plate 50 include apertures 70 and 36 for receipt of first dowel pin 30 and second dowel pin 32, respectively. Each of dowel pins 30, 32, 66 and 68 are retained with snap rings 73.

[0022] Vane 52 includes a rotary piston 74 having a generally cylindrical first end 76 and an elongated, substantially rectangular, second end 78. An opposed pair of co-axially aligned trunions 80 outwardly protrude from rotary piston 74 along axis 34. Each of trunions 80 includes an outer face 82. A central aperture 84 extends through first end 76 along axis 34. A plurality of apertures 86 are circumferentially positioned about aperture 84 and extend through first end 76 substantially parallel to aperture 84. Vane 52 includes a pair of grooves 88 continuously extending about its periphery. A pair of seals 90 are disposed within grooves 88. Each of seals 90 sealingly engage body 46, first cover plate 48, second cover plate 50 and vane 52 to prevent pressurized fluid from passing thereby.

[0023] With reference to FIGS. 2 and 9, first cover plate 48 and second cover plate 50 each include a bearing aperture 92. Trunions 80 are positioned and rotatably supported within bearing apertures 92. A pair of elastomeric o-rings 94 are positioned between each trunion 80 and each cover plate within apertures 92. Body 46, first cover plate 48 and second cover plate 50 are interconnected by a plurality of threaded fasteners 96 and correspondingly internally threaded nuts 98.

[0024] Arm assembly 24 includes a pair of rotary side plates 100, a rotary mount block 102, a stop plate 104, a contact bolt 106 and a shock absorber 108. Each of the rotary side plates are substantially flat plates constructed from 6061-T651 Aluminum. Rotary mount block 102 is preferably constructed from 4140 HRS. Each rotary side plate includes a plurality of threaded apertures 110 formed therein. Rotary mounting block 102 includes a plurality of counter bores 112. Threaded fasteners 114 rigidly couple rotary mounting block 102 to rotary side plates 100.

[0025] Each rotary side plate 100 includes a central aperture 116 aligned with central aperture 84 of vane 52. One of the central apertures of the rotary side plates includes a hexagonal cross-sectional shape to retain a nut 118. The other central aperture is substantially cylindrically shaped to accept the head of a cap screw 120. Each rotary side plate also includes a plurality of apertures 122 circumferentially positioned about central aperture 116. Drive pins 28 are slidingly disposed within apertures 122 to accurately align and drivingly couple arm assembly 24 to vane 52. A thrust plate 124 is positioned between each rotary side plate 100 and each outer face 82 of trunions 80.

[0026] Each rotary side plate 100 also includes a plurality of flats 126 positioned about a portion of its periphery. A corresponding number of threaded apertures 128 are positioned adjacent to flats 126 in a substantially circumferential manner. Flats 126 and threaded apertures 128 cooperate with a first trip bracket 130, a second trip bracket 131 and their associated threaded fasteners 132.

[0027] Each trip bracket is preferably “L” shaped and constructed from 1020 HRS. Each trip bracket includes a first leg 134 and a second leg 136. First leg 134 includes aperture 138 for receipt of fastener 132. Each trip bracket 130 and 131 cooperates with rotary status controller 26 as will be described in greater detail hereinafter.

[0028] Referring now to FIGS. 4-8, stop plate 104 is a generally planar member constructed from 6150 HRS. Stop plate 104 includes a pair of apertures 140 for receipt of fasteners 142. Fasteners 142 couple stop plate 104 to rotary mount block 102. Stop plate 104 also includes a contact surface 146 and an aperture 144 extending therethrough to provide clearance for a portion of shock absorber 108. Shock absorber 108 is coupled to rotary mount block 102. Shock absorber 108 includes an axially slidable piston 109 positioned to pass through aperture 144 and extend beyond contact surface 146 of stop plate 104. It should further be appreciated that shock absorber 108 is aligned to substantially orthogonally intersect second dowel pin 32 when actuated to rotate to the second position. Therefore, shock or impact type loading between stop plate 104 and second dowel pin 32 is avoided by assuring that shock absorber 108 dissipates most of the energy of rotation. Arm assembly 24 reaches the second position, as shown in FIG. 4, when contact surface 146 of stop plate 104 contacts second dowel pin 32.

[0029] A shock absorber 148 is coupled to body 46 and positioned to contact rotary mount block 102 when arm assembly 24 is rotated toward the vertical or first position shown in FIG. 3. Contact bolt 106 is coupled to rotary mount block 102 and is preferably constructed from hardened steel. Contact bolt 106 is positioned to substantially orthogonally intersect first dowel pin 30 once arm assembly 24 reaches the fully vertical first position. Shock absorber 148 is positioned to contact rotary mount block 102 prior to contact bolt 106 contacting first dowel pin 30. Thus, impact loading between contact bolt 106 and first dowel pin 30 is substantially eliminated.

[0030] As best shown in FIG. 3, the vertical or first position is a fixed position defined by the location of first dowel pin 30 and contact bolt 106. The range of rotary travel of arm assembly 24 is defined by the position of second dowel pin 32. In the preferred embodiment, second dowel pin 32 may be placed in any one of seven apertures 36 spaced apart in increments substantially equal to 15 degrees. It is contemplated that a different number of apertures or a different spacing between apertures may be implemented without departing from the scope of the present invention.

[0031] To assist the user in determining the position of arm assembly 24, rotary status controller 26 is coupled to one of the first and second cover plates. Rotary status controller 26 includes a first proximity sensor 150 and a second proximity sensor 152 mounted within a housing 154. First trip bracket 130 is coupled to rotary side plate 100 at a location which corresponds to the vertical or first position. First trip bracket 130 remains at this location regardless of the actuation angle desired. Second trip bracket 131 is coupled to rotary side plate 100 by threadingly engaging fastener 142 with the appropriate aperture 140. The appropriate aperture 140 is defined as the aperture corresponding to the desired angular rotation of arm assembly 24. When setting the desired range of rotary displacement, both second dowel pin 32 and second trip bracket 131 must be repositioned if a new rotary stroke is desired.

[0032] Rotary status controller 26 outputs a signal 156 indicative of the position of arm assembly 24. Specifically, a first signal is output if arm assembly 24 is located at the first position. A second signal is output if arm assembly 24 is located at the second position. To assist the user within the manufacturing environment, rotary status controller 26, trip bracket 130 and trip bracket 131 may be mounted on the opposite side of rotary pivot unit 20.

[0033] In operation, rotary pivot unit 20 accepts a pressurized fluid, preferably air, at inlet ports 56 and outlet ports 58. A pressure differential is generated by a suitable power source such as an air compressor (not shown) across inlet ports 56 and outlet ports 58. Accordingly, vane 52 responds by rotating toward the low pressure port. It is anticipated that a generally flat, constant torque output will be generated by the rotary pivot unit of the present invention. Specifically, as vane 52 rotates, the force measured at a given distance from axis of rotation 34 will be substantially constant for each rotational position of vane 52. As such, the lifting capacity will be linearly related to the distance from axis 34 as depicted in FIG. 10. Vane 52 will continue to rotate until arm assembly 24 contacts first dowel pin 30 or second dowel pin 32 depending on the direction of rotation. The rotational direction of vane 52 may be reversed by simply pressurizing the opposite port.

[0034] While a preferred embodiment of the present invention has been disclosed herein, other aspects fall within the scope of the present invention. For example, other actuator to arm assembly coupling mechanisms may be employed which use additional links or fasteners to drivingly interconnect the vane to the arm assembly. Moreover, the total rotational angular range may be varied. While various materials have been disclosed, other materials may be employed.

[0035] The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims. 

What is claimed is:
 1. A positioning apparatus comprising: a housing having a chamber; a vane rotatably movable within said chamber; an arm coupled to said vane; and a workpiece coupled to said arm, wherein said arm and said workpiece rotate in response to rotation of said vane.
 2. The positioning apparatus of claim 1 further comprising at least one fluid port in communication with said chamber, said port allowing entry of fluid into said chamber to rotate said vane relative to said member.
 3. The positioning apparatus of claim 2 wherein said vane includes a portion directly in contact with said fluid.
 4. The positioning apparatus of claim 3 wherein said fluid is air.
 5. The positioning apparatus of claim 3 wherein said arm has a mass center and wherein said vane has a mass center and an axis of rotation, wherein said arm mass center is positioned substantially opposite said vane mass center across said axis of rotation.
 6. The positioning apparatus of claim 5 wherein said axis of rotation extends through said chamber.
 7. The positioning apparatus of claim 1 further including a second arm and a mount block, said mount block interconnecting said arm and said second arm wherein said arm and said second arm are positioned substantially parallel to each other in an offset relationship.
 8. The positioning apparatus of claim 1 further comprising a shock absorber, wherein rotation of said arm is limited by said shock absorber.
 9. The positioning apparatus of claim 1 wherein said vane provides a substantially constant torque output throughout a range of rotation of said arm.
 10. The positioning apparatus of claim 9 wherein said range of rotation of said arm is substantially equal to 105 degrees.
 11. A positioning apparatus comprising: a rotary actuator; and an arm drivingly coupled to said rotary actuator, wherein said arm at least partially surrounds said rotary actuator.
 12. The positioning apparatus of claim 11 wherein said arm is a generally “U” shaped member having substantially parallel side plate portions interconnected by a mount block, wherein at least a portion of said rotary actuator is positioned between said parallel side plate portions.
 13. The positioning apparatus of claim 12 wherein said arm and said actuator are drivingly coupled with a drive pin.
 14. The positioning apparatus of claim 11 further comprising an industrial work piece coupled to said arm.
 15. The positioning apparatus of claim 11 wherein said rotary actuator includes a vane rotatably positioned within a chamber and at least one fluid port in communication with said chamber, said port operably allowing entry of fluid into said chamber to rotate said vane relative to said chamber.
 16. A positioning apparatus comprising: a rotary fluid actuator having a plurality of pin apertures extending therethrough; an arm drivingly engaged with said rotary actuator; and a pin selectively disposed within one of said pin apertures to define a range of rotary travel of said arm by the presence of said pin in one of said pin apertures.
 17. The positioning apparatus of claim 16 wherein said arm includes a stop portion selectively engagable with said pin to limit said range of rotary travel of said arm.
 18. The positioning apparatus of claim 17 further including a second pin positioned within one of said pin apertures, said stop portion being positioned between said pin and said second pin, said stop portion being engagable with said second pin to further limit said range of rotary travel.
 19. The positioning apparatus of claim 17 further including a shock absorber coupled to said stop portion.
 20. The positioning apparatus of claim 19 wherein said shock absorber contacts said pin before said stop portion contacts said pin.
 21. The positioning apparatus of claim 18 further including a shock absorber coupled to said rotary fluid actuator, said shock absorber contacting said stop portion of said arm prior to said stop portion contacting said second pin.
 22. A method of operating a rotary pivot unit having a rotary fluid actuator, an arm and a pin, the method comprising: (a) inserting the pin in one of a plurality of apertures extending through the actuator, the aperture positions corresponding to a desired range of rotational travel; (b) supplying fluid to the rotary actuator; (c) rotating a portion of the actuator by direct contact with the fluid; (d) rotating the arm in response to movement of the portion of the actuator; and (e) limiting the rotation of the arm by engaging the arm with the pin.
 23. The method of claim 22 further including inserting a second pin in another of said plurality of apertures to further limit the range of rotational travel of the arm to positions between the pin and the second pin.
 24. The method of claim 23 further including outputting a signal indicating the position of the arm.
 25. The method of claim 22 further including mounting an industrial tool to the arm thereby causing the industrial tool to rotate in response to rotation of the arm. 